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대형 풍력터빈 모형의 공력 성능 및 후류 유동장에 대한 비교 연구
정두원(Duwon Jeong),원영수(Young Soo Won),강승희(Seung-Hee Kang) 한국가시화정보학회 2019 한국가시화정보학회지 Vol.17 No.2
A comparison study between computational-fluid-dynamics simulation and wind tunnel test for a megawatt-class wind turbine is conducted. For the study, flow-field in wake, basic aerodynamic performance, and effect of the yaw error for a 1/86 scaled-down model of the NREL offshore 5 MW wind turbine are numerically calculated using commercial software “FloEFD” with k-ε turbulence model. The computed results are compared to the wind tunnel test performed by the constant-velocity mode for the model. It is shown that discrepancy are found between the two results at lower tip-speed ratio and higher yaw angle, however, the velocity-defection distribution in the wake, the torque coefficient at moderated and high tip-speed ratios are in good agreement with the wind tunnel test.
김동일,박종구,원영수 韓國海洋大學校電波通信硏究所 1999 電波通信硏究所論文集 Vol.1 No.-
전자공학 및 전파 통신기술의 눈부신 발전은 우리의 생활을 풍요롭게 해주는 반면, 전파의 사용증가로 인한 EMC대책이 사회적으로 중요하게 부각되고 있다. EMI/EMC 측정을 위한 전파무향실이 국제기준을 만족하려면 이를 구성하는 전파흡수가 30 ㎒ - 1 ㎓까지의 주파수 대역에서 20 ㏈ 이상의 전파흡수능을 가져야 한다. 그러나, 1998년 11월 CISPR11은 주파수대역을 30 ㎒ - 18 ㎓까지 확장하였다. 본 논문에서는 위의 조건을 만족하는 십자돌기형 및 테이퍼진 십자돌기형 전파흡수체를 제안하고 등가재료정수법으로 광대역 설계하였다. 나아가서, 그 결과를 FEM 및 FDTD법의 결과와 비교하였다. The remarkable progress of electronics and radio communications technology has made our life abundant. On the other hand, the countermeasure of EMC becomes more important socially according to the increased use of electromagnetic waves. It had been required that the absorbing ability of an electromagnetic wave absorber is more than 20 ㏈, the bandwidth of which is required through 30 ㎒ to 1,000 ㎒ for satisfying the international standard about an anechoic chamber for EMI/EMS measurement. From November of 1998, however, the CISPR11 has accepted the extended frequency band from 30 ㎒ to 18 ㎓ in the bandwidth of EMI measurement. In this paper, we proposed the cross-shaped type and tapered cross-shaped type absorbers satisfying the above requirments and carried out broadband design using the equivalent material constants method. Futheremore, the results have been compared with FEM and FDTD.